Marjorie in Command by Carolyn Wells — Read

ARBOR DAY was the most beautiful day you ever saw. Not too warm, or too cool, or too wet, or too dry, or too cloudy, or too bright-but just perfect in every way. The festival was to be held both afternoon and evening, and Miss Larkin told the children they might go at two o'clock, when it opened, and stay until nine at night.

Of course, this meant they would eat their supper there, which was a satisfactory arrangement to them all.